A Cautious Call For Start of Seasonal Arctic Re-Freeze

Six days after the typical end to the Arctic melt season shows some pretty clear evidence of a beginning to seasonal re-freeze. JAXA shows sea ice extent more than 250,000 square kilometers above the record low set just a few days ago. Cryosphere Today is showing sea ice area about 150,000 square kilometers above the record low also set at that time.

Though it is possible for melt to resume, each day of refreeze makes that potential less likely.

It is worth noting that NSIDC seems to also be calling for the melt season’s end with its new record low value of 3.41 million square kilometers having posted on September 16th and called the final low on September 19th. This value of 3.41 million square kilometers is a departure of 760,000 square kilometers below the record low set in 2007 and an 18% loss since that record low year.

Total losses for NSIDC sea ice extent are now 66% below best estimates for sea ice extent averages in the 1950s, 57% from the 1979 figure, 51% below the 1979-2008 average, and 18% below the last record low. By all long, medium, and short term measures, these departures show a consistent and devastating trend of sea ice extent loss. Volume losses, according to PIOMAS are now 78% below 1979, but final measurements for September aren’t yet in. So we can, potentially, expect greater volume losses once PIOMAS issues its report for this month.

The Arctic has suffered a devastating blow from which it is unlikely to significantly recover. Sea ice measures for area are more than 2.44 million square kilometers below the average for 1979-2008 and more than 3.5 million square kilometers below the typical measurement for this time of year in 1979. Measurements are also still about 500,000 square kilometers below the values during the extreme record melt season of 2007. That said, thin, one-year ice will likely show significant growth during the fall and winter months even as average values are likely to remain below the baseline extent for 1979-2008. In fact,with values so low for this year, it is possible that a number of months during fall and winter 2012-2013 will see record low averages and that summer 2013 will emerge more fragile than even 2012.

These measurements and assessments, if nothing else, show that this refreeze is just a small respite in a much larger melt trend that has been ongoing since at least the 1950s and is trending for an ice-free or near ice-free Arctic within the next 3-20 years.